Water is essential to many home activities (e.g., washing, cleaning, cooking, drinking, gardening). In 2008, it was estimated by the Environmental Protection Agency (EPA) that 36 states will face serious water shortages in the next five years. Furthermore, in 2001, the American Water Works Association indicated that only a 15% reduction in water usage across US households would save an estimated 2.7 billion gallons/day and more than $2 billion/year. Adding to the problem is a more recent estimate by the EPA that more than 1 trillion gallons of water leak from the water systems in U.S. homes each year, which accounts for about 10% of the average home's water usage. The leaks can be in worn faucet and toilet valves, as well as leaks in the water lines installed in living structures. Most consumers have no mechanism to accurately measure their household water usage other than total consumption indicated on a monthly (or bi-monthly) water bill, which are based on periodic water meter readings. Further, the leaks occurring in household water systems often go undetected, since they are not evident to residents in a home. In order to better conserve water and stop leaks, it will be necessary to provide residents with information related to the water consumed with each type of water consumption activity, from washing a load of clothes in a washer, to taking a shower or flushing a toilet.
Previous work that was directed toward monitoring home water usage created an approach that has several drawbacks. For example, this earlier approach used microphones pressed against an exterior of specific water pipes in a residence, including a cold water inlet, a hot water inlet, and a waste water exit, to demonstrate recognition of several important activities based on patterns of water use, such as the series of fill cycles associated with a dishwasher. This earlier technique was unable to reliably differentiate among multiple instances of water usage by similar fixtures (e.g., the opening or closing of valves at each of multiple sinks or the flushing of multiple toilets within a home), could not reliably identify concurrent activities (e.g., a toilet flush while a person is showering), and did not attempt to estimate the volume of water being used by the water system during water consuming activities. There are also significant difficulties in using the audio-based sensors due to ambient noise (e.g., noise produced by an air conditioning unit that is installed in close proximity to a sensor placed on a home's hot water heater). In addition, this prior approach did not enable leaks to be detected at specific fixtures.
In several industrial applications, such as irrigation systems, sensors providing high-granularity flow rate monitoring have been used, but these prior art approaches are either prohibitively expensive for residential use (e.g., from about $2,000 to about $8,000 for a single ultrasonic or laser Doppler velocimetry sensor) or require a professional installation by a plumber of multiple inline flow sensors. An inline flow sensor is installed for each fixture of interest by cutting into existing pipes. It has also been shown in a laboratory environment that accelerometers mounted on the exterior of water pipes produce a signal having a strong deterministic relationship to water flow rate, but this effect is highly sensitive to pipe diameter, material, and configuration. Others have proposed using a home's existing aggregate water flow meter together with a network of accelerometers on pipes to infer flow rates throughout a home. However, all of these prior art approaches require placement of multiple sensors along or in water pipe pathways that are uniquely associated with each fixture of interest (i.e., they are distributed direct sensing methods that cannot use a single sensor to monitor all of the fixtures in a structure water system).
It is therefore evident that it would be desirable to employ a better method and system for monitoring water flow to each of a plurality of different fixtures in a residence or multi-living unit structure that is low in cost and easily installed without using a plumber. Such a system and method should enable water usage or volumetric flow occurring at each fixture to be readily determined. In addition, it would also be desirable to employ such a system and method to detect water leakage at specific fixtures or points in a water system of a structure, so that a location of at least certain types of the leaks can be identified, to facilitate correcting the condition that has caused the leak.